And to be honest, it's not common sense to be angry. It's completely understandable that plans change because people are busy. What you are really angry about is that people don't make time for you and don't value your friendship. It has nothing to do with being busy but the other person, unless they truly are busy, do not value you the way you value them and yeah that sucks but that's life.

I've been best friends with someone since I was 14. He does not value me or my time at all. He's busy, busy, busy, can't even return a phone call but oh wait, hey, I just showed up at your door out of the blue. Let's go. You do make many good points in your rant, and I wish I had the steel heart to tell these friends no, I don't want to be friends with you because you do not value my time. It's not something I can easily do. I can't just shut down a friendship without crossing the line for me to refuse to be friends. I have, but it's definitely not easy.